1. Field of the Invention
The present invention relates to a medical device having an image pickup section that is able to pick up images of a tube cavity in a subject, more particularly, to a medical device that performs examination or treatment with high accuracy using virtual endoscopic images of a tube cavity in body based on three-dimensional image data of a subject.
2. Description of the Related Art
In recent years, diagnoses have been widely made using three-dimensional images. For example, a diagnosis for a target site can be made using three-dimensional image data of a subject which is obtained by picking up tomographic images of the subject with an X-ray CT (Computed Tomography) apparatus.
In the CT apparatus, a subject is continuously moved while X-ray radiating positions and detection positions are continuously rotated for continuous helical scanning of the subject (helical scan). A large number of resulting continuous two-dimensional tomographic images of the subject are used to create a three-dimensional image.
A three-dimensional image of bronchus of lungs is one type of the three-dimensional images used in diagnoses. Such a three-dimensional image of bronchus is used in a three-dimensional detection of the position of a diseased area with suspected lung cancer for example. In order to check the diseased area by a biopsy, a bronchus endoscope is inserted into the subject and a biopsy needle or biopsy forceps are extended out from a distal end portion of the bronchus endoscope, so as to collect tissue samples of the target site.
In a tract such as bronchus in a body that is branched in multiple steps, in a case where a diseased area is located at the end of a bronchus, it is hard to bring the distal end of an insertion section of an endoscope to a position near the target site in a short period of time with accuracy. Thus, for example, Japanese Patent Application Laid-Open Publication No. 2004-180940 and Japanese Patent Application Laid-Open Publication No. 2005-131042 disclose navigation systems for insertion of endoscope in which a three-dimensional image of a tract in a subject is created based on image data of a three-dimensional area in the subject, and route along the tract to a target on the three-dimensional image is determined, so that virtual endoscopic images of the tract along the route can be created based on the image data.